Custom Item Creation - Problems with Descriptions

Hey all.

Having some troubles with getting custom descriptions to work without overwriting existing item descriptions. I'm pretty comfy with creating items (using DLTCEP) and have got them working in game, along with the descriptions as well...but they seem to overwrite descriptions of other items.

I started just by opening an existing item, making whatever changes, then saving with a different file name so I don't overwrite the original...DLTCEP does the rest (have the dialog.tlk in the base BG2EE folder, it gets updated, then I copy to the EN-US folder....and I do have a backup of the dialog.tlk so I'm able to undo things easily). I'm finding that the custom description is overwriting the original item (though seemingly the item's actual abilities remain unaltered).

So next I tried creating an item from scratch. The above attempt was making a Carsomyr +5 long sword, but this scratch test I kept it simple (just a Long Sword +1 that adds 1d4+1 fire damage). I didn't start with any base long sword in DLTCEP, just made a new item altogether. I copied out the unidentified and identified descriptions though from a Long Sword +1, and just added 1d4+1 to the damage line for the identified description. Gave it a custom name (Widow's Fire +1), custom file name for the override folder....and it all worked until I saw the description for the plain Long Sword +1 had the added fire damage bit. Tested both in-game...Widow's Fire did it's added fire damage, the plain Long Sword +1 did it's thing (no fire damage)....but durn it, that description.

So yeah. I'm stumped. Been digging around in Google land and thus far I'm coming up blank.

I do have the BG2Tweak pack installed (some components of it, not all), but that's it, no other mods. Any help would be greatly appreciated (I have no plan to distribute whatever I make...they're just for personal use and fun).